This invention relates to certain Group 4 metal complexes comprising two ligand groups bonded to the metal by means of .PI.-electrons, at least one of which is a cyclic, or noncyclic, non-aromatic, anionic, dienyl group wherein the metal of said complexes is in the +2, +3, or +4 formal oxidation state and further wherein the two .PI.-bonded ligand groups are also bonded together via a divalent moiety. The invention also relates to techniques for preparing such complexes, catalyst systems comprising such complexes that are useful for polymerizing addition polymerizable monomers, and to such polymerization processes themselves.
Metal complexes containing delocalized, .PI.-bonded ligand groups and methods for their preparation are disclosed in U.S. application Ser. No. 545,403, filed Jul. 3,1990 (EP-A-416,815); U.S. application Ser. No. 547,718, filed Jul. 3, 1990 (EP-A-468,651); U.S. application Ser. No. 702,475, filed May 20, 1991 (EP-A-514,828); U.S. application Ser. No. 876,268, filed May 1, 1992, (EP-A-520,732) and U.S. application Ser. No. 8,003, filed Jan. 21, 1993 (WO93/19104), as well as U.S. Pat. No. 5,055,438, U.S. Pat. No. 5,057,475, U.S. Pat. No. 5,096,867, U.S. Pat. No. 5,064,802 and U.S. Pat. No. 5,132,380. The teachings of all the foregoing patents, publications and patent applications are hereby incorporated by reference.
In Organometallics, 10, 3643-3647, (1991) there were disclosed certain bridged 2,4-dimethylpentadienyl complexes of Ru and Yb. At page 3647 the authors speculated as to other applications for the ligand groups without mentioning any specific uses therefor.
Despite the advance in the art brought about by the foregoing metal complexes, new and improved catalytic compounds are still desired.